2002 Agronomy Abstracts

DIVISION A-3

Modeling Silage Quality as a Function of Weather and Soil. T.B. WILSON*, University of Wisconsin-Madison; D.R. MERTENS, USDA-DFRC, Madison, WI; J.M. NORMAN, University of Wisconsin- Madison.

Have Eddy-Flux Measurements Improved Over 30 Years. J.M. NORMAN, University of Wisconsin - Madison; J.M. BAKER, USDA/ARS, University of Minnesota.

DIVISION A-6

Phosphorus losses from alfalfa and grasses after freezing or drying. T. ROBERSON, L.G. BUNDY, and T.W. ANDRASKI. Univ. of Wisconsin.

DIVISION A-7

How to Set Up and Use a GPS-Based GIS for Increased Efficiency of Agricultural Research Station Management. J.A. GRODECKI, D.H. MUELLER*, B. BOWEN, M. DUDKA, R.F. HARRIS, S.J. VENTURA, University of Wisconsin - Madison.

DIVISION A-8

Yield Goal Versus Delta Yield to Predict Nitrogen Need in Corn. J.A. LORY, P.C. SCHARF, University of Missouri; L.G. BUNDY, University of Wisconsin.

The Imperative of Multiscale Analysis of Post-Industrial Agriculture. W. L. BLAND and M. GIAMPIETRO.

DIVISION A-9

How Can We Reduce Volatilization Losses? L.G. BUNDY*, University of Wisconsin-Madison.

How Do We Diagnose and Manage Soil Compaction? R.P. WOLKOWSKI ,University of Wisconsin-Madison.

DIVISION S-1

Linking Flux Footprint Analysis with Soil Spatial Heterogeneity. J.M. BAKER*, USDA-ARS, St. Paul, MN and University of Minnesota; J.M. NORMAN, University of Wisconsin-Madison; M.G. DUSAIRE, University of Minnesota; C. MOLLING, C.S. MORGAN, University of Wisconsin-Madison; D.R. COBOS, University of Minnesota.

Continuous Measurement of Water and Solute Fluxes in Soil. K.C. MASARIK, J.M. NORMAN, University of Wisconsin; K.R. BRYE, University of Arkansas; J.M. BAKER, University of Minnesota.

Saturated Hydraulic Conductivity versus Soil Permeability Classes: Facts, Fiction, and the Future.D.A. WYSOCKI*, NRCS-National Soil Survey Center; P.J. SCHOENEBERGER, USDA-NRCS, Lincoln, NE; B. LOWERY, University of Wisconsin; R. PAETZOLD, USDA-NRCS, Lincoln, NE.

DIVISION S-2

Phytate determination in Dairy Feces. T.J. BOERTH*, P.A. HEMLKE*, University of Wisconsin- Madison.

Effect of pH on Copper Complexation by Fulvic Acid. J.A. HOWE, P.A. HELMKE, W.F. BLEAM, University of Wisconsin-Madison.

DIVISION S-4

Using the PSNT and Nitrogen Crediting to Improve Corn Nitrogen Recommendations. L.G. BUNDY*, T.W. ANDRASKI, University of Wisconsin.

Co-Kriging Spatially Significant Soil Variables Using Imagery and Yield Data. J.K. CURLESS*, L.K. BINNING, J.M. NORMAN, Univ. of Wisconsin-Madison.

Forage Cations as Affected by Soil pH and Topdressed K. J.B. PETERS*, K.A. KELLING, P.E. SPETH, S.M. OFFER, University of Wisconsin-Madison.

Dairy Diet Effects on Manure Nitrogen Excretion and Cycling in Soils. J.M. POWELL, USDA-ARS, Madison, WI.

DIVISION S-5

Accelerated Aging of Agricultural Soils and the Coupling of the Nitrogen and Proton Cycles. M. AVILA*, P. BARAK, J.L. POSNER, University of Wisconsin-Madison; D.A. LAIRD, National Soil Tilth Laboratory.

The Virtual Museum of Minerals and Molecules Presents Soil Nanoscapes.P. BARAK, Univ. of Wisconsin-Madison; E.A. NATER, University of Minnesota-Twin Cities.

Challenges of Determining Carbon Pools in Arctic Tundra Soils.J.G. BOCKHEIM*, Univ. of Wisconsin; J.M. KIMBLE, USDA-NSSC, Lincoln; C. TARNOCAI, Agriculture & Agri-Food Canada; K.M. HINKEL, Univ. of Cincinnati; W.R. EISNER, Univ. of Cincinnati; C.L. PING, Univ. of Alaska-Fairbanks.

Geochemical indicators of weathering and redox in laterite formation. D.J. BROWN, Montana State University; P.A. HELMKE, University of Wisconsin - Madison.

Terrain and parent material controls on texture contrast in Uganda: GLS regression and thin- plate splines.D.J. BROWN, Montana State University; M.K. CLAYTON, K. MCSWEENEY, J.M. NORMAN, University of Wisconsin - Madison.

Automation of the Nine-Unit Landsurface Model using a Neuro-fuzzy Network.P.K. FALK, K. MCSWEENEY, University of Wisconsin-Madison.

Soil Landscape Modeling: the Promise and Limitations of Quantitative Approaches.K. MCSWEENEY, C.L. MORGAN, J.M. NORMAN, University of Wisconsin-Madison.

3-D Simulations of Heat and Water Flow in Landscapes with Heterogeneous Soils. C.C. MOLLING, J.M. NORMAN, University of Wisconsin - Madison.

Genesis and Morphology of Soils Associated with Laguna Bocana in Palo Verde National Park, Costa Rica.C.A. STILES, C.I. MORA, S.G. DRIESE, S.P. HORN, The University of Tennessee.

DIVISION S-6

Phosphorus Losses from Alfalfa and Grasses after Freezing or Drying. T. ROBERSON, L.G. BUNDY, T.W. ANDRASKI, University of Wisconsin-Madison.

Analysis of Diurnal Patterns of Soil Water Fluctuation in Irrigated Potato. G.C. STARR, USDA-ARS New England Plant, Soil, and Water Laboratory, Orono, ME; E.T. COOLEY, Door County Soil and Water Conservation Department; B. LOWERY, University of Wisconsin - Madison.

DIVISION S-7

Linking P Forms to the Microbial Community in the Forest Floor Along a Hawaii Chronosequence.B.J. CADE-MENUM, Stanford University; T.C. BALSER*, University of Wisconsin, Madison.

Base-cation Cycling by Individual Tree Species in Old growth Hardwood-hemlock Forests of Sylvania Recreation Area, Upper Michigan.R. FUJINUMA*, J.G. BOCKHEIM, N.J. BALSTER, University of Wisconsin - Madison.

DIVISION S-8

Incubation trial examining mineralized N using various labeled manure components and soils.P.R. CUSICK*, Univ. of Wisconsin- Madison; J.M. POWELL, USDA-ARS, Madison, WI; R.F. HENSLER, Univ. of Wisconsin- Stevens Point; K.A. KELLING, Univ. of Wisconsin- Madison.

Estimating Second- and Third-year Nitrogen Availability from Dairy Manure. K.A. KELLING*, P.R. CUSICK, J.M. POWELL, G.R. MUNOZ, P.E. SPETH, Univ. of Wisconsin-Madison.

Influence of Time of Manure Application on Potato Yield, Quality and Scab.M.A. DAWSON* K.A. KELLING P.E. SPETH, W.R. STEVENSON, University of Wisconsin-Madison.

Inorganic Amendments as Golf Course Putting Green Construction Materials.D.J. SOLDAT*, W.R. KUSSOW, University of Wisconsin - Madison.

DIVISION S-9

Sorption of Sulfonamide Antibiotics to Clay Minerals. J.A. PEDERSEN*, University of Wisconsin - Madison.

DIVISION S-11

Biogenic Phosphate Minerals in Poultry Litter and Implications for Preventing Eutrophication. L.R. COOPERBAND and L. W. GOOD, Univ. of Wisconsin-Madison.

DIVISION A-3

Modeling Silage Quality as a Function of Weather and Soil . T.B. Wilson*, University of Wisconsin-Madison; D.R. Mertens, USDA-DFRC, Madison, WI; J.M. Norman, University of Wisconsin- Madison.
A dairy forage assessment framework is presented to characterize the variability of silage quality related to climate variations during the crop growing season. The framework was applied to current commercial corn hybrids devoted to silage production systems located in the dairy production region of U.S. The main objective was to evaluate the effects of weather on the quality value and relative maturity of corn silage and the relation of relative maturity to quality value. Quality value data used were obtained from a large number of field experiments conducted by Pioneer Hybrid, Inc, and implemented in geographically different dairy producing states of the U.S. from 1998 to 2001. The main weather information used was daily series of precipitation and maximum and minimum air temperatures for each study site obtained from the NOAA-NCDC. After analyzing the variations in the datasets, quality values and relative maturity were correlated by multiple regression to the weekly average values of different weather variables. These models suggest that region differences exist and weather variability can explain 40-60% of quality values.

Have Eddy-Flux Measurements Improved Over 30 Years . J.M. NORMAN - University of Wisconsin - Madison, J.M. BAKER - USDA/ARS, University of Minnesota.
Micrometeorological measurements of surface fluxes have been made by the eddy-covariance method for over 30 years. George Thurtell was one of the first persons to make such measurements in the U.S. in the mid 1960's. Great advancements have been made in instrumentation since the early days when a thousand-pound computer, 10 kW of power and a 22-foot trailer were required. Today, reliable turn-key systems are available for long-term measurements of heat, water vapor and carbon dioxide fluxes at modest cost. Numerous advancements have been made in refining and correcting minor errors in the measurements. However, our basic understanding of how these measurements relate to turbulent processes at various scales in the surface layer and planetary-boundary layer seems to have lagged behind instrumentation advances and remains little changed from 30 years ago. Even coordinate rotations commonly used today were originally derived and published by George Thurtell, and uncertainties noted then remain today. Wider acceptance of the systematic underestimation of surface fluxes by eddy covariance has drawn more attention to its shortcomings, but little progress in addressing these issues is apparent.

DIVISION A-6

Phosphorus losses from alfalfa and grasses after freezing or drying . T. Roberson, L.G. BUNDY, and T.W. ANDRASKI. Univ. of Wisconsin.
Phosphorus released from plants after freezing at the end of the growing season may be a contributor to P in runoff from agricultural landscapes. We evaluated P release from alfalfa ( Medicago sativa L.) and mixed grass species after freezing or drying in laboratory and field studies. Freezing plants in the laboratory or in-field treatment with the herbicide paraquat (1,1'-dimethyl-4, 4'-bipyridinium ion) greatly increased water-extractable P, with more P extracted from grasses than from alfalfa. Alfalfa grown on soils with excessive P soil test levels released more P after freezing than plants grown on soils with optimum P levels. Alfalfa leaves contained more water extractable-P than stems based on P release after freezing. Runoff from paraquat-treated alfalfa or grass field plots subjected to simulated rainfall contained higher P concentrations than runoff from untreated plants. The effects of natural freezing of alfalfa on P losses in runoff were evaluated by collecting runoff from alfalfa and control plots during the over winter period.

DIVISION A-7

How to Set Up and Use a GPS-Based GIS for Increased Efficiency of Agricultural Research Station Management . J.A. Grodecki, D.H. Mueller*, B. Bowen, M. Dudka, R.F. Harris, S.J. Ventura, University of Wisconsin - Madison.
A global positioning system (GPS)-based geographic information system (GIS) has been successfully implemented for management of the Arlington Agricultural Research Station (ARS), and there is interest in applying it to other stations. The Rhinelander ARS was used to document a step-by-step process for efficiently setting up a GPS-based GIS, providing a guide of what to do and what not to do. Spatial data are maintained in ArcView GIS and field records in Microsoft Access. GPS data are collected using ArcPad 6.0 software in the Wisconsin Transverse Mercator (WTM) coordinate system. An Avenue script customizing ArcView for ARS purposes is used to edit and update field boundaries, join tables in MS Access and ArcView, and compose and print maps. Data in non-WTM coordinates can be projected to WTM and added to ArcView project files. The GPS-based GIS is a valuable tool for creating a spatially referenced primary field boundaries map, calculating field acreage, tracking annual changes in subfield boundaries and crop rotations, and organizing information about field management and conditions for decisions on integrated agricultural production and water quality protection.

DIVISION A-8

Yield Goal Versus Delta Yield to Predict Nitrogen Need in Corn . J.A. Lory, P.C. Scharf, University of Missouri; L.G. Bundy, University of Wisconsin.
Many states use a yield goal to identify differences in fertilizer N need combined with an N credit system to adjust for N provided by the soil from sources such as soil organic matter and crop residues. Some question yield goal derived fertilizer N recommendations because of the poor correlation of yield and fertilizer N need, leading some states to eliminate yield goal from their N recommendation system. In this study, data from 298 previously reported experiments in five states (IL, MN, MO, PA and WI) were combined to evaluate fertilizer N response of corn. Corn grain yield at the economically optimum N rate was poorly correlated with fertilizer N need (r2=0.02). Most locations required a reduction in recommended N to account for N supplied by the soil or previous management. Delta yield (grain yield at optimum N rate minus grain yield with 0N applied) at the same locations was positively correlated with fertilizer N need and a much better predictor of fertilizer N need (r2=0.47). These results imply that fertilizer recommendation systems that rely solely on yield or ignore yield entirely are limited to explaining no more than 50% of the variation in fertilizer N need of corn.

The Imperative of Multiscale Analysis of Post-Industrial Agriculture . W. L. BLAND and M. GIAMPIETRO.
Analysis of the agricultural endeavors extant on a landscape and how research and policy might influence them requires recognition of constraints imposed by both larger and smaller scales. Upper-level constraints are imposed by societal and environmental contexts. Societal constraints include local standards of return to labor and prices paid for products. The environmental context includes resource availability and animal and plant performance. These contexts place limits on the viable activities a farmer could pursue-the option space. Farmer ingenuity can expand the option space, but only within the constraints imposed by upper-level contexts. The lower-level context is that of the farmer, and constraints here include land, human activity, capital stocks and flows, and the payoff function, i.e., what returns satisfy the farmer's values and aspirations. The farmer context shapes the mix of activities chosen from the option space to create a farm. The aggregate of these farms form the regional landuse pattern and agricultural economy. Agricultural research and extension must increasingly recognize this holarchical nature of farming systems.

DIVISION A-9

How Can We Reduce Volatilization Losses? L.G. Bundy*, University of Wisconsin-Madison.
More than 50% of the N fertilizer used in the USA contains urea. To optimize the agronomic performance of these fertilizers, N losses through ammonia volatilization must be controlled. Ammonia losses from urea-containing fertilizers are influenced by urea reactions in the soil and by soil, climate, and management factors. Surface applications, no rainfall after application, high crop residue cover, warm temperatures, and initially moist soils favor volatilization losses. Even when conditions are ideal for ammonia loss, the actual losses seldom exceed 20% of the applied N. Nitrogen source comparisons with surface-applied materials often show better performance with non-urea fertilizers due to N losses from urea. Urease inhibitors can reduce ammonia loss, but economic benefits of these inhibitors are not consistent. Winter applications of urea on frozen soils and spring preplant applications on sandy soils may be subject to losses. Control measures for ammonia loss include incorporating or injecting urea- containing fertilizers, using non-urea N sources for surface applications, and using a urease inhibitor where the risk of volatile losses is high.

How Do We Diagnose and Manage Soil Compaction? R.P. Wolkowski ,University of Wisconsin-Madison.
The need to conduct field operations in a timely and productive manner has given rise to soil compaction concerns. Pressure from wheel traffic and tillage consolidate the soil and may destroy the soil structure. Compaction effects are long-term and are not quickly ameliorated by natural forces. The symptoms of compaction are visible by examining the response of the soil and crops. Compacted soils have imperfect drainage and massive structure. Compaction effects cause uneven plant growth and malformed root systems. Nutrient deficiencies, especially K, can develop in response to poorer soil aeration. Compaction almost always causes a yield loss. Excavate the soil to examine the soil structure and evaluate root distribution. A cone penetrometer can be used to measure the resistance to penetration, however it should only be used to make a relative comparison. Be sure to note the depth at which compaction occurs. Often subsoiling is considered when compaction problems are severe. Before deciding to subsoil it is important to diagnose the existence of compaction and to record the depth of the restrictive layer. Soil compaction problems will continue to be an issue in modern agriculture.

Division S-1

Linking Flux Footprint Analysis with Soil Spatial Heterogeneity . J.M. Baker*, USDA-ARS, St. Paul, MN and University of Minnesota; J.M. Norman, University of Wisconsin-Madison; M.G. DuSaire, University of Minnesota; C. Molling, C.S. Morgan - University of Wisconsin-Madison; D.R. Cobos - University of Minnesota.
When making flux measurements it is assumed that the surface is homogeneous. Soils research suggests that such surfaces are rare. Indeed the whole field of precision agriculture is premised on spatial, non- random variation in plant growth, and by extension, surface atmosphere exchange. Footprint analysis, a subject to which George Thurtell has been a key contributor, provides a means to estimate the relative contribution of different points on the landscape to a measured flux. Soil dielectric measurements, for which Clarke Topp is best known, allow characterization of landscape variation in soil properties that can lead to variation in surface fluxes. We used both technologies to interpret eddy covariance measurements above a corn field. We found that variations in surface horizon thickness are consistent with variations in cumulative carbon exchange rate, as manifested in yield. When yield variations are weighted by footprint to produce a cumulative flux for each direction from a central mast, the resultant varies by a factor of two, raising questions about the interpretation of long-term cumulative flux data at sites where there is spatial variation in source strength.

Continuous Measurement of Water and Solute Fluxes in Soil . K.C. Masarik, J.M. Norman, University of Wisconsin; K.R. Brye, University of Arkansas; J.M. Baker, University of Minnesota.
Evaluating the impact of land use practices on ground water quality has been difficult because no techniques are capable of monitoring the quality and quantity of soil water flow below the root zone without affecting the flow process. A recently introduced method, known as equilibrium tension lysimetry, was a major improvement but was not a true equilibrium since it required manual intervention to maintain proper suction. We addressed this issue by developing an automated equilibrium tension lysimeter system (AETL) that continuously matches lysimeter tension to water potential of the soil. The water potential of the bulk soil is measured with a heat dissipation sensor (HDS), while a small DC pump applied suction to the lysimeter. The automated approach was operated for a twelve-month period. Powered by a 12 V rechargeable battery the AETLs were able to operate effectively for two week periods with minimal human attention, along with the added benefit of collecting continuous soil-water potential data. We also demonstrated, in the laboratory, methods for continuous measurement of water depth in the AETL, a capability that makes them true water flux meters.

Saturated Hydraulic Conductivity versus Soil Permeability Classes: Facts, Fiction, and the Future. D.A. Wysocki*, NRCS-National Soil Survey Center; P.J. Schoeneberger, USDA-NRCS, Lincoln, NE; B. Lowery, University of Wisconsin; R. Paetzold, USDA-NRCS, Lincoln, NE.
Hydraulic conductivity of saturated soil (Ksat), the proportionality factor between the flux velocity and the hydraulic gradient, is an important soil water parameter. Need exists for both measured and estimated Ksat values. The NRCS Soil Permeability Classes are widely utilized as an estimated Ksat. Confusion persists on the relationship between Ksat and the Permeability Classes. Permeability Class(e.g., cm/hr), are a percolation rate that equals the flux (q) in Darcy's equation. The original percolation rate measurements employed both a variable and constant driving head with the hydraulic gradient greater than unity. Percolation rates exceed and have a none-uniform relationship to Ksat, but with prudence may be used as an estimated Ksat. Permeability Class values mathematically are not a proportionality factor (Ksat) and should not be substituted for Ksat in Darcy's equation. Conversely, a calculated Ksat from a field or lab measurement does not yield the percolation rate of the Permeability Classes. To alleviate confusion and avoid scientific inaccuracies, we recommend the use of Soil Ksat Classes rather than Soil Permeability Classes.

Division S-2

Phytate determination in Dairy Feces . T.J. Boerth*, P.A. Helmke*, University of Wisconsin- Madison.
A capillary electrophoresis method was developed to determine the total amount of phytate (myo-inositol hexaphosphate) in five percent trichloroacetic acid extracts of dairy feces. The total amount of phytate phosphorus in dairy feces ranges from fifteen to fifty percent of the total phosphorus. The amount of phytate in dairy feces is indirectly proportional to the amount of supplemental orthophosphate in the dairy ration. Approximately fifteen percent of the total phytate in dairy feces is mineralized by phytase.

Effect of pH on Copper Complexation by Fulvic Acid. J.A. Howe, P.A. Helmke, W.F. Bleam, University of Wisconsin-Madison.
Binding of copper(II) to dissolved soil fulvic acid was investigated using the Donnan Membrane Equilibrium (DME) technique. A soil II fulvic acid standard from the International Humic Substances Society was used at concentrations in the range of natural systems (10 to 100 mg/L). Copper complexes were made at pH 4 and 6 with a range of metal concentrations (0.01 to 17 mg/L). Unbound Cu was distinguished from total Cu by the DME technique and both free and total Cu were measured by graphite furnace atomic absorption spectroscopy (GF-AAS). A computer simulation based on a Gaussian distribution model was used to calculate formation constants for Cu and fulvic acid. Results indicate that binding of Cu at pH 4 is less than at pH 6, presumably due to the effect of pH on the hydrolysis of Cu binding functional groups.

Division S-4

Using the PSNT and Nitrogen Crediting to Improve Corn Nitrogen Recommendations . L.G. Bundy*, T.W. Andraski, University of Wisconsin.
Excess N use in crop production can lead to environmental problems and reduced economic returns. The presidedress soil nitrate test (PSNT) and N crediting for organic N inputs can improve the accuracy of corn N recommendations, but these techniques are often not used due to producer concerns about their reliability. This study compared using the PSNT and standard N crediting for legumes and manure for identifying optimum N rates and quantifying economic returns in 101 N response field experiments with corn (Zea mays L.) during 1989-1999. The accuracy of PSNT recommendations was highest for sites with average or above average May- June air temperatures and high soil yield potential. The frequency of excess N recommendations from the PSNT increased from 16 to 59% when May-June temperatures were >0.56 degrees C below average likely due to slower organic N mineralization. Use of N recommendations based on the PSNT or book value N credits (BVNC) lowered N rates by 90 to 102 kg/ha in systems with recent manure or legume N inputs and increased average economic returns for all cropping systems by 19 dollars/ha compared with unadjusted N recommendations. Economic gains using PSNT- or BVNC-based recommendations were generally highest in the first year following organic N inputs with an average gain of 34 dollars/ha for both methods. Conversely, economic gains were higher using the PSNT (40 dollars/ha) than the BVNC (2 dollars/ha) 1 to 3 yr after the organic N additions. Results from this work confirm that adjusting N application rates using the PSNT or BVNC is more profitable than not making these adjustments. This finding is in contrast to the common perception that complete crediting of organic N sources increases economic risk.

Co-Kriging Spatially Significant Soil Variables Using Imagery and Yield Data. J.K. Curless*, L.K. Binning, J.M. Norman, Univ. of Wisconsin-Madison.
The ability to predict fertility concentrations and its spatial distribution provides valuable information for managing fertility and yield variations within agricultural fields. To gain an understanding of plant and soil nutrient variability and how they influence (Zea mays) and (Glycine max) yields, a research study was conducted on a dry land production field in Northern Illinois. Research began in 1998 and continued through 2000 growing season near Shabbona, Illinois in a 25 ha production field. A soil sampling grid of 0.068 ha was established in 1998 on the production site. The grid assignment continued for the duration of the study for plant and soil samplings. Geostatical methods were used to analyze the dynamics of plant tissue, soil samples, soil conductivity, and yield for each season via spatial regression using SPlus. The analysis conducted proved to be a useful tool in detecting spatial variability of soil fertility concentrations and their influences on yield productivity. The spatially significant variables were Co- Kriged using correlated hyper spectral and multi spectral bands.

Forage Cations as Affected by Soil pH and Topdressed K. J.B. Peters*, K.A. Kelling, P.E. Speth, S.M. Offer, University of Wisconsin-Madison.
In recent years, concerns have surfaced relative to the amount of K in forage tissue, which is strongly influenced by soil test K levels as well as other factors. An ionic imbalance in the ration increases the potential for the cow to develop milk fever at freshening. This four-year study was designed to examine the interactive effects of varying soil pH levels and annual potassium applications on forage mineral balance, yield and quality. Results indicate that soil pH and applied K can both significantly influence forage yield, quality and cation levels. At all three locations where the study was conducted, as soil K increased, tissue K increased very dramatically, however, tissue Ca and Mg decreased to a much smaller extent. The annual application of K resulted in a buildup of soil test K and a decrease in soil test Ca and Mg. Increasing soil pH, and consequently soil test Ca, did not appear to consistently result in reduced tissue K levels. However, liming these acid soils was essential to optimize yields of alfalfa. Keeping soil test K levels in the optimum range appears to be the best strategy for keeping forage tissue K levels in acceptable ranges for use as dry cow and early lactation dairy feed.

Dairy Diet Effects on Manure Nitrogen Excretion and Cycling in Soils. J.M. Powell, USDA-ARS, Madison, WI.
Dairy cow excretion of urinary nitrogen (UN), fecal endogenous N (FEN) of microbial and gut origin and fecal undigested feed N (FUN) is highly affected by diet. A greenhouse trial was conducted to test the hypothesis that crop N uptake is affected by UN, FEN, and FUN applications. Dairy feces from 12 diets, and feces and urine from 4 diets, after mixing in the UN:total fecal N ratio as excreted and left standing for 24h to observed possible diet effects on ammonia loss, were applied at equivalent N rates (350 kg/ha) to 2 silt loam and 1 sandy loam soil and oats were grown for 45 days. For pots containing feces only, there were no interactive effects on oat N uptake between soil and manure types. Oats grown in silt loams had similar N recoveries (34 and 33% of total applied N), which were significantly lower than for the sandy loam (41%). Oat N uptake in pots that received approx. half of applied N as UN was similar (65%) across soil types. Across all diets, oat N uptake in pots containing only feces ranged from 28 to 40%, and in pots containing feces and urine from 53 to 81%. Application of feces and urine derived from different dairy diets significantly affected oat N uptake.

DIVISION S-5

Accelerated Aging of Agricultural Soils and the Coupling of the Nitrogen and Proton Cycles. M. Avila*, P. Barak, J.L. Posner, University of Wisconsin-Madison; D.A. Laird, National Soil Tilth Laboratory.
Agroecosystems currently utilize about one third of the soils of the world and, in these soils, crop management introduces new variables to the biogeochemical cycles governing soil development. N fixation related to human activities now accounts for about half of the global N budget and has greatly enhanced the role of the N cycle in soil biogeochemistry. Microbial oxidation of ammoniacal N in soils generates acidity far greater than does acid rain, leading to base cation leaching, loss of CEC, and accelerated mineral weathering, measurable over decades. Soil acidification reflects imbalanced N cycling in soils related to the oxidation status of N inputs, the cation/anion balance of nutrient uptake by crops, the net export of reduced N by crop harvest, and the leaching of nitrate and other anions. When acidity is neutralized by soil constituents, chemical changes in the soil properties- including saturation of the exchange complex with exchangeable acidity, depletion of base cations through leaching with anions, and the loss of cation exchange sites due to pH-dependent CEC or mineral weathering--determine the ability of soil to further neutralize acidity.

The Virtual Museum of Minerals and Molecules Presents Soil Nanoscapes. P. Barak, Univ. of Wisconsin-Madison; E.A. Nater, University of Minnesota-Twin Cities.
To the casual observer, the 'lay of the land' is readily visible with the turn of the head and the sweep of the eye. Trained observers, however, are aware that change of perspective or change of scale will turn familiar landscapes unrecognizable; a creekbed is part of a larger watershed, land has not only surface but unperceived depth and soil has not only matrix but microscopic minerals. The chemistry of soil processes occur on vast areas of soil surfaces and across millimeter-thick interfaces and are explainable at the molecular level--the soil nanoscape. The chemistry of the soil water is characterized by minute concentrations of exotic and ephemeral compounds produced by microorganisms and plants as they live in the voids of the soil matrix, immersed in the soil water, and adjacent to the soil surfaces. Such nanoscape worlds are so far removed from human sight that they can be presented only using virtual reality. The Virtual Museum of Minerals and Molecules, http://www.soils.wisc.edu/virtual_museum/ is a web-based collection of computer-generated models, both mineral and organic, that shows the nanoscale
structures where many important soil properties and processes reside.

Challenges of Determining Carbon Pools in Arctic Tundra Soils. J.G. Bockheim*, Univ. of Wisconsin; J.M. Kimble, USDA-NSSC, Lincoln; C. Tarnocai, Agriculture & Agri-Food Canada; K.M. Hinkel, Univ. of Cincinnati; W.R. Eisner, Univ. of Cincinnati; C.L. Ping, Univ. of Alaska-Fairbanks.
Whereas the cold ecoregion comprises 20% of the global land area, it contains 42% of the global soil C pool. In the Northern Hemisphere, dramatic increases in winter and spring air temperature since ~1970 have been accompanied by increases in the seasonal thaw layer, warming of permafrost, and a possible shift in Arctic Tundra from being a sink to a source for atmospheric CO2. There are several challenges in determining C pools in permafrost-affected soils, including high small-scale variability due to patterned ground, mixing of organic C into the subsoil by cryoturbation, the presence of large amounts of C in the permafrost at depths >1 m, the difficulties in scaling up from the pedon to the landscape or regional level, preparing soil C maps, providing soil C databases, and modeling warming impacts. In this paper we discuss how cryopedologists have addressed these challenges through specially adapted field techniques for Gelisols and scaling up through the use of ground penetrating radar and satellite imagery. The availability of soil C maps and databases is discussed.

Geochemical indicators of weathering and redox in laterite formation. D.J. Brown, Montana State University; P.A. Helmke, University of Wisconsin - Madison.
In this study of a laterite landscape on granitic rock in Uganda, we use Neutron Activation Analysis (NAA) to develop a suite of robust geochemical indices that can be applied at the landscape scale to study the role of weathering and oxidation-reduction (redox) processes in laterite formation. For landscape studies, with natural variability in bedrock composition and active geomorphic processes resorting materials, techniques developed for the geochemical analysis of profiles are of limited use. To capture K-feldspar weathering the K/Hf ratio serves as a good proxy for feldspar/zircon, K/Na indexes feldspar concentration to quartz. Mn-Ce-Ba nodules and concretions can be identified by characteristically high Ce values, with anomalies recorded as high as 5000ppm. We propose using the Fe/Sc ratio to ascertain the absolute (redox) vs. relative (weathering) Fe accumulation in laterite formation. The Fe/As ratio, indicative of the degree of co-precipitation of these elements, corroborates the Fe/Sc findings. The suite of indices developed in this study point to the importance of redox processes in the formation of laterite on this landscape.

Terrain and parent material controls on texture contrast in Uganda: GLS regression and thin- plate splines. D.J. Brown, Montana State University; M.K. Clayton, K. McSweeney, J.M. Norman, University of Wisconsin - Madison.
The catena concept posits that topographic controls on hydrology and parent material can be related to the spatial variability of soils at the landscape scale. On the landscape of origin for the catena concept in central Uganda, we test theories of texture-contrast formation by examining terrain and parent material controls on surface texture for the well-drained portion of the landscape. In this study, we use Generalized Least Squares (GLS) regression (regression with residual spatial covariance modeled explicitly) to support inferential analysis of individual controls on soil formation. Terrain-derived indices (e.g. slope and curvature) are computed directly from a thin -plate spline model fit to elevation data, allowing the smoothing parameter to control the scale of topographic variability examined. Surprisingly, the results suggest that parent material composition and relatively fine-scale convexities (decayed termite mounds) have a greater effect on surface texture than hillslope-scale features.

Automation of the Nine-Unit Landsurface Model using a Neuro-fuzzy Network. P.K. Falk, K. McSweeney, University of Wisconsin-Madison.
Some soil landscapes are complex and prove difficult to spatially render without copious sampling, which may not be feasible due to constraints of time and money. To address this problem, a benched hillslope in southwestern Wisconsin was classified as to membership in the Nine-Unit Landsurface Model. Soil sampling was minimal, with sites mainly restricted to a few transects. A Digital Terrain Model was developed from a GPS survey. TAPES-G was used to determine terrain attributes, which were classified as to land surface unit using a fuzzy neural network. The fuzzy classification was displayed using ARCVIEW, as were soil attributes known to vary with bench location; percent organic matter, A-horizon thickness, fine to medium silt and clay fractions and profile thickness. Attribute coverages were unable to rectify the benches, considerably more sampling would be needed for a realistic representation; whereas, the fuzzy classification depicted benches and other hillslope features. Information about a specific site can be inferred from the landsurface unit definition. For complex soil landscapes, this approach offers an alternative to costly and time consuming sampling.

Soil Landscape Modeling: the Promise and Limitations of Quantitative Approaches. K. McSweeney, C.L. Morgan, J.M. Norman, University of Wisconsin-Madison.
Partitioning water across a landscape is a complicated process to model due to the dynamic interface of vegetation, rainfall, and soil properties. Previous research on soil landscape modeling has focused on infiltration at the millimeter scale and runoff on the meter or landscape scale. A vital aspect of landscape modeling is to represent the biophysical processes that regulate water partitioning at both scales with equal levels of quantitative rigor, while maintaining the ability to parameterize the equations with readily available sources of soil information. For example, a macropore flow subroutine in the Precision Agricultural Landscape Modeling System, PALMS, uses soil structure and shrink swell information available in USDA Soil Survey books for parameterization. The flow of water through soil macropores is calculated using basic physical equations that describe geometry of slits and pores created by soil structure. The differences of water partitioning across a landscape and throughout soil horizons are shown for two soil-management cases that affect soil structure.

3-D Simulations of Heat and Water Flow in Landscapes with Heterogeneous Soils. C.C. Molling, J.M. Norman, University of Wisconsin - Madison.
The Precision Agricultural Landscape Modeling System (PALMS) is a biophysical process model simulating physical processes and plant growth on heterogeneous landscapes. Point-column processes are simulated on 5x5 to 20x20 meter grid cells. These processes include heat, water, and CO2 exchange from the free atmosphere, through plant canopy, to the surface; above and below ground plant physiology; and distribution of energy, water, and nutrients in the soil down to 5.5 meters. Processes on individual grid cells are connected through overland flow of water that includes effects of soil roughness and tillage interactions with topography. Results from several PALMS simulations will be shown in graphical form, primarily water movement on the landscape surface, and the movement of heat and water in the soil. Results will emphasize the interactions among topography, soil heterogeneity, and management (tillage type and timing). Widespread use of PALMS will depend strongly on meaningful and easily approachable methods of visualizing model output. A few examples of the problems of visualizing 3D data are discussed and ideas regarding creative solutions are presented.

Genesis and Morphology of Soils Associated with Laguna Bocana in Palo Verde National Park, Costa Rica. C.A. Stiles, C.I. Mora, S.G. Driese, S.P. Horn, The University of Tennessee.
Soils near Laguna Bocana, Palo Verde Park, Costa Rica, have remarkable amounts of gypsum at 40-80 cm depth (5-20 wt%). Low H2O pH (mean = 4.8) and reduced matrix colors suggest these soils undergo seasonal redox fluctuations, and sulfur occurs either as gypsum in the dry season (maximum evapotranspiration), or as mixed reductive phases during flooding. Previously classified as Vertisols, we found vertic fabrics disrupted by displacive gypsum growth, and ostensibly re-classified them as Inceptisols, although taxon may be seasonally changeable. Paddy irrigation exacerbates salt accumulation near wetlands and strongly influences soil quality and vegetational communities in the park.

DIVISION S-6

Phosphorus Losses from Alfalfa and Grasses after Freezing or Drying. T. Roberson, L.G. Bundy, T.W. Andraski, University of Wisconsin-Madison.
Phosphorus released from plants after freezing at the end of the growing season may be a contributor to P in runoff from agricultural landscapes. We evaluated P release from alfalfa (Medicago sativa L.) and mixed grass species after freezing or drying in laboratory and field studies. Freezing plants in the laboratory or in-field treatment with the herbicide paraquat (1,1'-dimethyl-4, 4'-bipyridinium ion) greatly increased water-extractable P, with more P extracted from grasses than from alfalfa. Alfalfa grown on soils with excessive P soil test levels released more P after freezing than plants grown on soils with optimum P levels. Alfalfa leaves contained more water extractable- P than stems based on P release after freezing. Runoff from paraquat-treated alfalfa or grass field plots subjected to simulated rainfall contained higher P concentrations than runoff from untreated plants. The effects of natural freezing of alfalfa on P losses in runoff were evaluated by collecting runoff from alfalfa and control plots during the over winter period.

Analysis of Diurnal Patterns of Soil Water Fluctuation in Irrigated Potato. G.C. Starr, USDA-ARS New England Plant, Soil, and Water Laboratory, Orono, ME; E.T. Cooley, Door County Soil and Water Conservation Department; B. Lowery, University of Wisconsin - Madison.
Irrigated potato production in the central sands region of Wisconsin suffers from rapid drainage and concurrent chemical and nutrient transport to groundwater. Soil water content time series were measured across a potato hill in sandy soil using time domain reflectometry to evaluate water flow and uptake patterns. Hydrophobic dry zones developed in the center of potato hills and relatively wet soil persisted at the base. Diurnal variations were evident in the root zone when soil was not excessively dry. The temporal profile of the diurnal soil water cycle indicated a direct link with evapotransporation. The power in the diurnal peak of spectral density was calculated, and this may be a diagnostic indicator of localized water removal by roots and evaporation. The hydrophobic zone is problematic because root uptake from that area ceases, sprinkler irrigation does not penetrate effectively, and water is diverted toward a rapidly draining base region of the potato hill. Management practices targeted at improving soil wetting properties or altering water flow toward the center of the hill would likely improve water use and production efficiency under these conditions.

DIVISION S-7

Linking P Forms to the Microbial Community in the Forest Floor Along a Hawaii Chronosequence. B.J. Cade-Menun, Stanford University; T.C. Balser*, University of Wisconsin, Madison.
Using forest floor samples from a Hawaiian chronosequence, we determined P forms and concentrations with 31-P NMR and related them to microbiological parameters determined by PLFA and BiOLOG. Total and organic P followed the same trends as total C and N: lowest in samples from the youngest and oldest sites, and highest at the mid-aged sites. The greatest diversity of P forms from NMR was found in samples from the mid-aged site, which also had the highest microbial biomass. Monoester P was highest at the youngest sites, decreased significantly with age, and correlated positively with pH. Diester P was highest in the mid-aged site, correlated positively with C and N, and negatively with fungi and eukaryotes. Pyrophosphates and phosphonates were seen in all samples, with no differences with age, and did not correlate with any microbial groups. Polyphosphates were seen only in samples from the mid- aged site, and correlated with actinomycetes. These results suggest that monoester P is controlled by the soil chemical environment, while diester P is controlled by soil biota. Phosphonates appear to be controlled by climate and soil chemistry, accumulating in wet, acid soils.

Base-cation Cycling by Individual Tree Species in Old growth Hardwood-hemlock Forests of Sylvania Recreation Area, Upper Michigan. R. Fujinuma*, J.G. Bockheim, N.J. Balster, University of Wisconsin - Madison.
The influence of individual tree species on base-cation (Ca, Mg, K, Na) distribution and cycling was examined beneath sugar maple (Acer saccharum Marsh.), basswood (Tilia americana L.), and hemlock (Tsuga canadensis L.) in mixed hardwood - hemlock forests in northwestern Michigan. Base cation pools (biomass, forest floor, mineral soil) and fluxes (bulk precipitation, throughfall, stemflow, litterfall, forest floor leachate, mineralization, and soil leachate) were estimated for five replicated trees on a sandy, mixed, frigid, Typic Haplorthod during the 2000 and 2001 growing seasons. Sugar maple distributed more base cations in biomass whereas basswood and hemlock distributed them in the mineral soil. Base- cation fluxes generally are ranked: basswood > sugar maple > hemlock. Although the differences in inputs among tree species during the growing season are small compared to the size of pools, they produce significant differences in base-cation pools over a single life cycle (ca. 250 years). These differences in base-cation pools and fluxes are important with regards to the sustainability of mixed hardwood hemlock ecosystems in the upper Great Lakes region.

DIVISION S-8

Incubation trial examining mineralized N using various labeled manure components and soils. P.R. Cusick*, Univ. of Wisconsin- Madison; J.M. Powell, USDA-ARS, Madison, WI; R.F. Hensler, Univ. of Wisconsin- Stevens Point; K.A. Kelling, Univ. of Wisconsin- Madison.
The rate and extent of manure N mineralization in soil determines manure N availability for crop uptake. A laboratory incubation study was conducted in which 15N-labeled or unlabeled feces, urine and oat straw bedding were mixed with 6 soils of differing physical and chemical characteristics. Manure N equivalent to 350 kg/ha (36% derived from feces, 42% from urine and 22% from bedding) was applied to incubation vessels (2L glass jars containing 250g soil dry wt.) in the following combinations: 1) 15N- labeled feces with urine and bedding at natural abundance, 2) 15N-labeled urine with feces and bedding at natural abundance), 3) 15N-labeled bedding with feces and urine at natural abundance, and 4) all components 15N-labeled. Triplicate vessels per manure treatment plus controls were kept at 60% water filled pore space and incubated at 11, 18, or 25C. Vessels were sampled at 0, 14, 21, 42, 84, and 168 days and were analyzed for mineralized N (NH4 and NO3) and 15N abundance. Based on the average mineral 15N content in all soils at 168 days (25C), we estimate that 15, 48, 16, and 30 percent of the fecal, urine, bedding, and total manure N had mineralized over the course of the study.

Estimating Second- and Third-year Nitrogen Availability from Dairy Manure . K.A. Kelling*, P.R. Cusick, J.M. Powell, G.R. Munoz, P.E. Speth, Univ. of Wisconsin-Madison.
It is common practice to repeatedly apply dairy manure to the same fields. To accurately assess the total plant availability of manure nutrients, it is necessary to account for the nutrients remaining in soil from previous years applications. A corn (Zea mays) field experiment has continued since 1998 on a Plano silt loam. Residual manure N availability was estimated for two and three years after a single manure application from differences in whole-plant N uptake using 1) fertilizer N equivalence 2) the difference method and 3) 15N labeled manure. Second year availability using the fertilizer equivalence and difference method was estimated to be 7.3 and 2.6% of total manure N applications respectively. Third year availability was estimated to be 7.6 and 3.3%. Estimates of 15N recovery were 5.3 and 2.3% for second and third year availability, respectively. Fertilizer equivalent and difference methods showed great variability making it difficult to accurately estimate residual manure N availability, but was much reduced using the 15N method. However this approach also requires a fertilizer comparison to estimate relative use efficiency and accurately establish an N credit.

Influence of Time of Manure Application on Potato Yield, Quality and Scab. M.A. Dawson* K.A. Kelling P.E. Speth W.R. Stevenson, University of Wisconsin-Madison.
This study evaluates whether the timing of applying manure can reduce the negative impacts preceding potatoes. Four potato varieties; Russet Norkotah, W-1151R (a very scab-susceptible variety), Snowden and Superior, were planted in May 2001 to evaluate the influence of time of manure application prior to potato planting on tuber yield, quality, and the incidence of common scab. Liquid dairy manure was applied at a rate of 280,500L/ha in Nov. 1999, Nov. 2000 or April 2001. Fertilizer was applied to the no manure plots at N and P rates equivalent to the available N and P in the Nov. 2000 manure application. Harvest data showed a significant interaction between time of manure application and variety. With two of the varieties (R. Norkotah and W-1151R) as the manure application was made closer to planting, tuber yield and dry matter decreased, however, for Snowden and Superior the length of time between manure application and planting had no effect on these parameters. The former varieties also tended to show more scab with the more recent manure applications (p=0.14). Therefore, a high application rate of manure one month before planting has a negative effect on yield and quality.

Inorganic Amendments as Golf Course Putting Green Construction Materials. D.J. Soldat*, W.R. Kussow, University of Wisconsin - Madison.
Use of inorganic amendments in golf putting green root zone mixes has recently become of interest. Inorganic amendments such as zeolites and porous ceramics are desirable because of their high CEC and water retention capacity. Cost of the materials currently limits their widespread use. The purpose of this study is to quantify the agronomic, environmental, and economic benefits of these inorganic amendments to justify their cost. An experimental putting green was constructed using sand amended with two types of zeolites, a porous ceramic material, peat moss, and pure sand as a control. Leachate is being monitored for mineral nitrogen, phosphorus, and potassium content. The amount of nitrogen, phosphorus, and potassium found in the leachate is being related to turfgrass growth and clipping nutrient content. Laboratory analysis has shown that phosphorus adsorption and desorption is controlled by the calcareous sand rather than the amendments. Initial leachate data suggest that the amendments have little effect on potassium leaching, the zeolites exhibit less nitrogen leaching than the other treatments, and the porous ceramic material releases relatively high levels of phosphorus.

DIVISION S-9

Sorption of Sulfonamide Antibiotics to Clay Minerals. J.A. Pedersen*, University of Wisconsin - Madison.
Sulfonamide antibiotics represent a large class of synthetic, primarily bacteriostatic agents finding both human and veterinary use. These compounds enter soil and subsurface environments through the disposal and use of human and animal wastes. Interaction of sulfonamide antibiotics with particle surfaces controls their leaching, subsurface transport, susceptibility to degradation and promotion of antibiotic resistance. Sorption of sulfonamide antibiotics to soils is greater than would be expected from compound hydrophobicity suggesting that mechanisms in addition to hydrophobic partitioning to natural organic matter play a significant role in their association with soil particles. Specific interactions with clay mineral surfaces may contribute to the greater than expected sorption of these compounds. To investigate this possibility, we examined the association of selected sulfonamide antibiotics with whole soils and reference clay minerals.

DIVISION S-11

Biogenic Phosphate Minerals in Poultry Litter and Implications for Preventing Eutrophication. L.R. COOPERBAND and L. W. GOOD, Univ. of Wisconsin-Madison.
Excess manure phosphorus applied to croplands has increased P losses in runoff and surface water eutrophication. When poultry litter (PL) and dairy manure (DM) were applied to the same soil at the same total P rate, the potential for P loss in runoff was greater from the DM. Poultry litter contains sparingly soluble calcium and magnesium phosphate mineral phases that control water-extractable P concentrations in PL-amended soil, while DM does not. Using scanning electron microscopy coupled with energy dispersive spectroscopy, we found mineral phosphates in PL that resemble biological calcium-magnesium phosphates such as kidney stones. Inositol hexaphosphate (phytate) may be associated with these particles. Our findings show that, in contrast to current models, different animal manures must be managed differently to minimize P losses.